A fast method for analyzing samples in the pharmaceutical industry is ion mobility spectrometry, an analytical technique that characterizes chemical substances based on their gas-phase ion mobilities. These mobilities are determined by measuring drift velocities as ions move, under the influence of an electric field, through a gas at ambient pressure. The method can be up to two orders of magnitude faster and can be much cheaper than other methods, such as liquid chromatography (LC). Moreover, unlike LC, ion mobility spectrometry does not require highly trained personnel to administer the test.
In ion mobility spectrometry, an analyte, such as a pharmaceutical compound, is ionized and then inserted into a drift tube. The ions migrate downfield and strike a collector electrode, producing a current. The ion current is amplified and displayed as an ion mobility spectrum or plasmagram, showing ion current versus time. Such a plasmagram can be used to characterize the pharmaceutical compound.
Ion mobility spectrometry, therefore, involves two major steps: in the first step, a sample is prepared and inserted into the analyzer, and in the second step, the sample is analyzed. While some variations in the second step exist, not too many options are available for preparing and inserting the sample for analysis.
Often, the introduction step involves the use of a solution of analyte in a solvent. Unfortunately, the presence of solvents during the analysis stage can yield poor reproducibility and spurious plasmagrams. Therefore, any different method that could improve the introduction step, by increasing reproducibility, by increasing the number of solvents that can be used for analysis, or by allowing greater variability in sample size, would be most welcome.